Abstract
Amorphous silica–aluminas were prepared by the sol-gel method using carboxylic acids, malic acid (MA), succinic acid and citric acid, and the reactivity for catalytic cracking was investigated. When the ratio of MA/TEOS (tetraethoxysilane) increased, surface area, pore volume and pore diameter increased and mesopores were formed. The maximum total conversions of n-dodecane were around 30% with the single amorphous silica–alumina. In contrast, the total conversion reached 91% with the single beta-zeolite. To investigate the reactivity of amorphous silica–alumina as a matrix, mixed catalysts consisting of zeolite, amorphous silica–alumina and binder (alumina sol) were prepared. The product distribution changed compared with the single zeolite or silica–alumina, and comparable activity to that of zeolite was obtained although the mixed catalysts included only 1/4 of zeolite. Mixed catalysts using amorphous silica–alumina with mesopores (MA122-5) exhibited higher ratio of multi-branched to single-branched products in the gasoline fraction (C5-C11) than single zeolite. The effect of the addition of 1-dodecene and 1-methylnaphthalene was also investigated.
